MORE than 4,500 patients tested at Hereford County Hospital for a range of illnesses may have been misdiagnosed.

Now tissue samples from 4,525 people are being re-checked and a special helpline set up for anyone concerned they may be affected.

Letters have also been sent to the patients involved - in Herefordshire and border areas - telling them what is happening.

The review was ordered after concerns about possible errors in the examination of the samples by a consultant histopathologist working in Hereford County Hospital's lab between May 2006 and August 2007.

Chief executive Martin Woodford said he personally apologised on behalf of the trust to all patients affected by "such regrettable action", especially to those who may have had a wrong diagnosis.

"Our highest priority is the care and wellbeing of our patients and we are acting as quickly as possible to make sure the review is carried out thoroughly and effectively," he said.

Results from the re-testing, by an external, independent laboratory, are already coming back.

Of the 5,245 samples from 4,525 patients, 2,796 have been dealt with. In 2,131 cases the original result has been confirmed.

So far, 12 patients have been identified to be recalled to see their consultant or GP. Six have already done so and, in one case, there has been a "minor" change in treatment.

Medical director Alison Budd said about 200 patients could be recalled.

Cross-checking and quality control in the hospital lab are being reviewed and an additional histopathologist recruited.

A hospital trust statement said all the samples were examined by one consultant over 15 months. No concerns had been raised about the accuracy of reporting by any other member of the histopathology department.

The consultant is no longer working at the hospital and the trust would only add that there were no doubts about the work of other staff in the unit. The samples under review are about a third of the total dealt with by the lab during the period.

Most were taken from patients attending the hospital, with some from GPs.

They include tissue from biopsies, surgical specimens and cytology and cover a whole spectrum of conditions, including lumps, inflammatory symptoms, rheumatoid conditions or bowel diseases - but none relate to blood or urine tests, swabs or X-rays.

The reviews should be complete by the end of the month and patients notified of the outcome.

Any patient who has had samples tested at the hospital lab, but not had a letter, should not be concerned because only the work of one consultant is being reviewed.

Mr Woodford said the trust had delayed telling patients until testing was well under way to avoid the stress of waiting months for the results.

The helpline, which runs from 9am to 9pm every weekday and from 9am to 1pm on Saturday and Sunday, is on 01432 363980.